Higher-Density Culture in Human Embryonic Stem Cells Results in DNA Damage and Genome Instability

Here, the authors demonstrate a direct correlation between medium acidification linked to culture density and the occurrence of DNA damage and genomic alterations in hESC grown on feeder layers. This, in turn, results in an increase of cells in G1 and a stalling of the S phase, without an increase in cell death or a loss of pluripotency. The DNA effects are rapid and occur in the short time span of a single passage. However, culture density has no effect on the level of apoptosis. Increasing the frequency of the medium refreshments minimizes the levels of DNA damage and genetic instability. hESC grown on laminin-521 show a decreased proneness to acquiring DNA damage during suboptimal culture conditions, such as medium acidification during high culture density.